Add changelog

Author: DylanRussell

CHANGELOG.md

@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Overwrite logging.config.fileConfig and logging.config.dictConfig to ensure
 the OTLP `LogHandler` remains attached to the root logger. Fix a bug that
 can cause a deadlock to occur over `logging._lock` in some cases ([#4636](https://github.com/open-telemetry/opentelemetry-python/pull/4636)).
+- Add new environment variables to the SDK `OTEL_PYTHON_EXPORTER_OTLP_{METRICS/TRACES/LOGS}_CREDENTIAL_PROVIDER` that can be used to
+inject a `requests.Session` or `grpc.ChannelCredentials` object into exporters created during auto instrumentation.
 
 ## Version 1.35.0/0.56b0 (2025-07-11)